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Date: Thu, 8 Jul 2010 11:00:33 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: "Ma, Ling" <ling.ma@intel.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH -tip] Revert x86, mem: Optimize memcpy by avoiding
	memory false dependece
Message-ID: <20100708150033.GA10224@Krystal>
References: <20100708062733.GA24740@Krystal> <20100708071153.GH4414@elte.hu>
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* Ingo Molnar (mingo@elte.hu) wrote:
> 
> * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> 
> > * Ma, Ling (ling.ma@intel.com) wrote:
> > > Hi Mathieu
> > > 
> > > I did git revert as bellow
> > >     Revert "x86, mem: Optimize memcpy by avoiding memory false dependece"
> > > 
> > >     This reverts commit 77ff5e49c20bb72a99a12bfb00dbf90b2302f087.
> > > And I found the machine will crash with your config file
> > > 
> > > Could you revert the patch : 77ff5e49c20bb72a99a12bfb00dbf90b2302f087 on your
> > > machine, and check it again ?
> > 
> > Hi Ling,
> > 
> > I just successfully booted my machine 3 times in a row with a revert of 
> > commit a1e5278e40f16a4611264f8da9e557c16cb6f6ed from -tip. This is actually 
> > the same as reverting commit 77ff5e49c20bb72a99a12bfb00dbf90b2302f087, as 
> > a1e5278e40f16a4611264f8da9e557c16cb6f6ed is simply a merge of that commit 
> > (the diffs are exactly the same).
> > 
> > Without this revert, the machine gets to:
> 
> Please check latest -tip (2a74852 or later), the commit should be gone now.

Will do, thanks!

Mathieu

> 
> There's clearly some (boundary-condition?) bug in the assembly code of 
> 77ff5e49c2.
> 
> Thanks,
> 
> 	Ingo

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com